A smart card or chip card as presently used consists of a card of approximately the same size as a standard credit card that contains intelligence on the card itself. This intelligence is typically in the form of a memory circuit which can contain read only memory or read/write memory (random access memory) contained on the card. The information stored in the card's memory can then be used by the card reader or card interface device to detect certain information stored on the card, such as an instantaneous bank balance. The information stored in the card's memory can also be instantaneously updated, for example the alteration of the security status of a specific badge holder. Cards of this type can also be used with cable television decoders or descramblers and with satellite systems.
Although the preferred embodiments of this invention are specifically directed to smart cards, it is equally applicable to connectors or similar devices. For example this invention would be applicable to the use of connectors for smart keys and could even be used for memory cards of the type generally referred to as PCMCIA cards.
Card readers or connectors for use with smart cards typically employ data contacts to engage pads on the cards themselves. These card readers or connectors generally employ an end position or end of stroke switch to detect full insertion of the card into the connector. These end position switches can be either normally closed switches which are opened when the smart card is fully inserted or normally open switches which are closed by insertion of the card. When the state of the switch is detected, the card reader or interface device is activated and data is transmitted to or from the smart card.
Among the problems which must be overcome for card connectors and card readers of this type to attain a satisfactory level of performance is that the connectors must function for a large number of card insertions, and the card connector must function in environments which can cause deterioration or damage to the contact interface of the data contacts and the end position switches. Typically the card connectors will be used in applications, such as in automatic teller machines or in security devices, where a large number of cards will be used with a single card connector or reader. Over time the cards used in these applications can become deformed and can collect foreign substances which can interfere with the operation of the card reader. The card connectors can also be used in environments, such as outdoor use in automatic teller machines, where they are susceptible to environment contaminants, or in which oxides could build up over time. Since these applications employ relatively low electrical potential and current, the energy present in power applications to burn off these contaminants or oxides is not available. Therefore it is desirable that a wiping contact between the data contacts and the card contact pads be established to insure removal of contamination from the contact area. This wiping contact, however, must not be accompanied with excessive force which might damage the plating on the data contacts or the resilient data contacts themselves. Similarly, a wiping contact action is desirable on the end position switch contacts for the same reasons.
One method of employing a wiping contact for the end position switches is to use to resilient switch contact elements which undergo relative and absolute motion during mating contact. U.S. Pat. No. 4,900,273, U.S. Pat. No. 5,013,255, and U.S. Pat. No. 5,334,034 each disclose smart card readers or connectors which employ end of stroke switch contacts using two resilient blades or beams to impart a wiping or self cleaning action during mating engagement. One problem which each of these devices embody is that two resilient end position switch contacts invariably occupy more space than one resilient beam. Therefore the card connectors in which they are used tend to be somewhat larger than would otherwise be necessary. In many, and perhaps most, applications space is critical, especially the printed circuit board space which is occupied by the card connector. For example, a larger card connector might dictate the use of a double sided printed circuit board instead of a single sided printed circuit board with the added cost inherent in the double sided board.